From 70d892b38c105b1ce08b3d77ae526ebeccb5c672 Mon Sep 17 00:00:00 2001
From: Bradley Lowekamp <blowekamp@mail.nih.gov>
Date: Mon, 22 Dec 2025 15:05:20 -0500
Subject: [PATCH] WIP: Conform GDCM to use CMAKE_*OUTPUT_DIRECTORY

Add GDCM support for modern CMAKE_*_OUTPUT_DIRECTORY
variables. Removes setting legacy CMake cache variables.

Internlly GDCM still uses the legacy names.
---
 Modules/ThirdParty/GDCM/src/CMakeLists.txt    |  4 --
 .../ThirdParty/GDCM/src/gdcm/CMakeLists.txt   | 41 ++++++++++++++-----
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/Modules/ThirdParty/GDCM/src/CMakeLists.txt b/Modules/ThirdParty/GDCM/src/CMakeLists.txt
index 9b99de751a3..3bae00a5447 100644
--- a/Modules/ThirdParty/GDCM/src/CMakeLists.txt
+++ b/Modules/ThirdParty/GDCM/src/CMakeLists.txt
@@ -63,10 +63,6 @@ set(GDCMV2_0_COMPATIBILITY ON CACHE INTERNAL "")
 set(GDCM_WRITE_ODD_LENGTH OFF CACHE INTERNAL "Do not change")
 set(GDCM_DEBUG_POSTFIX "" CACHE INTERNAL "")
 
-# GDCM uses these to refer to executable and library locations
-set(EXECUTABLE_OUTPUT_PATH ${CMAKE_RUNTIME_OUTPUT_DIRECTORY})
-set(LIBRARY_OUTPUT_PATH ${CMAKE_LIBRARY_OUTPUT_DIRECTORY})
-
 add_subdirectory(gdcm)
 
 foreach(lib
diff --git a/Modules/ThirdParty/GDCM/src/gdcm/CMakeLists.txt b/Modules/ThirdParty/GDCM/src/gdcm/CMakeLists.txt
index 09f298a08f5..d828b51a7c0 100644
--- a/Modules/ThirdParty/GDCM/src/gdcm/CMakeLists.txt
+++ b/Modules/ThirdParty/GDCM/src/gdcm/CMakeLists.txt
@@ -118,20 +118,39 @@ if(BUILD_SHARED_LIBS)
 endif()
 
 #-----------------------------------------------------------------------------
-if(NOT EXECUTABLE_OUTPUT_PATH)
-  set(EXECUTABLE_OUTPUT_PATH ${GDCM_BINARY_DIR}/bin CACHE PATH "Single output directory for building all executables.")
-  mark_as_advanced(EXECUTABLE_OUTPUT_PATH)
+# Compatibility with older usage of EXECUTABLE_OUTPUT_PATH and LIBRARY_OUTPUT_PATH.
+# This should be removed in the future.
+if(EXECUTABLE_OUTPUT_PATH)
+  set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${EXECUTABLE_OUTPUT_PATH})
+  message(WARNING "EXECUTABLE_OUTPUT_PATH is deprecated. Use CMAKE_RUNTIME_OUTPUT_DIRECTORY instead.")
 endif()
-if(NOT LIBRARY_OUTPUT_PATH)
-  set(LIBRARY_OUTPUT_PATH ${GDCM_BINARY_DIR}/bin CACHE PATH "Single output directory for building all libraries.")
-  mark_as_advanced(LIBRARY_OUTPUT_PATH)
+if(LIBRARY_OUTPUT_PATH)
+  set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBRARY_OUTPUT_PATH})
+  set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBRARY_OUTPUT_PATH})
+  message(WARNING "LIBRARY_OUTPUT_PATH is deprecated. Use CMAKE_LIBRARY_OUTPUT_DIRECTORY and CMAKE_ARCHIVE_OUTPUT_DIRECTORY instead.")
 endif()
 
-# TODO: The following should be used for CMake 3 and beyond,
-# EXECUTABLE_OUTPUT_PATH and LIBRARY_OUTPUT_PATH are deprecated
-set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${EXECUTABLE_OUTPUT_PATH})
-set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBRARY_OUTPUT_PATH})
-set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBRARY_OUTPUT_PATH})
+if(NOT CMAKE_RUNTIME_OUTPUT_DIRECTORY)
+  set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/bin)
+endif()
+if(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
+  set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/bin)
+endif()
+if(NOT CMAKE_ARCHIVE_OUTPUT_DIRECTORY)
+  set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/bin)
+endif()
+
+# Set for legacy internal usage of EXECUTABLE_OUTPUT_PATH and LIBRARY_OUTPUT_PATH
+if (NOT EXECUTABLE_OUTPUT_PATH)
+  set(EXECUTABLE_OUTPUT_PATH ${CMAKE_RUNTIME_OUTPUT_DIRECTORY})
+endif()
+if (NOT LIBRARY_OUTPUT_PATH)
+  if (BUILD_SHARED_LIBS)
+    set(LIBRARY_OUTPUT_PATH ${CMAKE_LIBRARY_OUTPUT_DIRECTORY})
+  else()
+    set(LIBRARY_OUTPUT_PATH ${CMAKE_ARCHIVE_OUTPUT_DIRECTORY})
+  endif()
+endif()
 
 #-----------------------------------------------------------------------------
 # Adding GDCM_DATA_ROOT